Rotary drill bit



April 12, 1949.

Filed June 6, 1945 A. W. KAMMERER ROTARY DRILL BIT 2 Sheets-Sheet l 3 ARC/1'57? Jaw/M52512,

[N V EN TOR.

ATTORNEY.

A ril 12,1949.

filed June 6, 1945 'IHHIIIIHI A? W. KAMMERER ROTARY DRILL BIT 2 Sheets-Sheet 2 particularly to bits of Patented Apr. 12, 1949 UNITED STATES PATENT OFFICE ROTARY DRILL BIT Archer W. Kammerer, Fullerton, Calif.

Application June 6, 1945, Serial No. 597,744

15 Claims.

This invention relates to drill bits, and more the expanding type for drilling or reaming larger diameter holes below well casing than the inside diameter of such casing through which the bit is capable of passing.

It is an object of the present invention to provide an improved expansible rotary well drilling bit of simple and sturdy construction, which can be operated by the driller in much the same manner as the usual non-expanding rotary drill bits.

Another object of the invention is to provide an improved expansible rotary well drilling bit whose cutter parts are movable outwardly to a predetermined expanded position, and positively prevented from returning from such position to retracted position until drilling weight is removed from them.

Yet another object of the invention is to yieldably urge cutter members outwardly to a prededetermined position and then look them in such outward position until drilling weight is no longer imposed upon them, which will automatically allow their return to retracted position.

A further object of the invention is to provide an expansible rotary well drilling bit whose shiftable cutter parts are initially held in retracted position by positive means, which are releasable hydraulically upon reaching the desired operative position of the bit in the bore hole.

In its general aspects the invention contemplates an expansible rotary well drilling bit adapted to be lowered through well casing on the end of a string of drill pipe to a location below the casing at which a drilling or reaming operation is to commence. During the lowering operation the bit cutters and their supporting members remain in retracted position by riding the inner wall of the casing, or, if desired, they may be held positively in retracted position :by latching means.

Upon reaching the well bore location where the drilling operation is to commence, the drilling string and attached drill bit are rotated to cause the cutters to produce a formation shoulder under the outward cutter expanding influence of elastic or spring means. The extent of this outward expansion of the cutters is predetermined by a positive stop arrangement which governs the maximum diameter of the hole being drilled or reamed. After the full formation shoulder has been produced, drilling weight is imposed downwardly on the drill string to move a lock device into an operative position holding the cutters positively in an outward direction, and preventing their inward return movement until desired. After downward drilling or reaming of the de- 2 sired length of hole, the drilling weight is removed from the bit, enabling a retracting device to automatically shift the lock device and cutter mechanism into such relative positions as to permit retraction of the latter andupward removal of the tool from the well bore.

In the event that the positive, retracting latch device is used, circulating pumps must first be started to eject the latch device hydraulically, permitting functioning of the elastic or spring cutter expanders and their urging of the cutters outwardly against the wall of the bore hole to produce the aforementioned formation shoulder.

The invention has other objects which will become apparent from a. consideration of the embodiment shown in the drawings accompanying and constituting part of the present specification. This form of the invention will now be described in detail to illustrate the general principles of the invention, but it is to be understood that such detailed description is not to be taken in a limited sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

- Figure 1 is a side elevation of one form of drill bit embodying the invention;

Figure 2 is a longitudinal section through the drill bit, with parts shown in retracted position for lowering through the well bore;

Figure 3 is a view similar to Figure 2 with the parts shown in expanded position;

Figure 4 is a cross-section taken along the line 4-4 of Figure 3;

Figure 5 is a cross-section taken along the line 55 in Figure 3; and

Figure 6 is a partial longitudinal section taken along the line 6-6 in Figure 3.

As shown in the drawings, the rotary drill bit A is attached to a string of drill pipe B, by means of which it is lowered through a well casing in a well bore to a. point below the casing shoe D at which enlargement of the bore hole is to start. The drill bit preferably has a pilot bit H) at its lower end for centering the bit in a hole that may have already been drilled, or for drilling the central portion of new hole in the absence of a. pre-existing hole. The main portion of the bit is capable of enlarging the bore hole by producing and operating upon a formation shoulder E, as hereinafter described.

The upper end of the bit consists of a driving mandrel l l whose upper pin I 2 is threadedly connected to a sub l3 forming the lower end of the drill pipe string B. This mandrel includes an upper kelly or drill stem member M slidably 3 'splined to the main body I5 of the bit. As disclosed in the drawings, the exterior E41 of the kelly is hexagonal in shape and is telescopically received in a companion hexagonal socket I5a Within the body. The mandrel has a limited range of longitudinal movement within the body, its upward movement being limited by engagement of an external shoulder I6 on the kelly with a retainer ring I! at the upper end of the body,

suitably secured thereto, as by welding material I8.

The body I5 has a, plurality of expansible parts mounted on it, comprising opposed cutter supporting members I9, I9 pivotally carried between bifuricated body arms 20, on pivot or hinge pins 2|, 2|, suitably secured to the arms, as by welding material 22. Each cutter supporting member includes a depending leg 23 having a bearing supporting pin 24 inclined inwardly and downwardly, and on which is rotatably mounted a roller side cutter 25. Antifriction roller and ball bearing elements 25, 21 are preferably placed between each cutter 25 and bearing pin 24, the roller bearings 26 transmitting radial thrusts and the ball bearings 21 both radial and axial thrusts. The ball bearings 21 also retain the cutter on the pin, being inserted in place through a passage 28 in the bearing support which is then closed .by a plug 29 welded to the pin.

Each cutter supporting member I9 also includes an upwardly extending arm 30 against which an elastic expander 3| bears. This expander, in the form of a compressed coil spring, is received within a retainer pocket 32 in the body I5 and exerts its force against the arm 30, tending to swing it inwardly and thus urge the cutter 25 on the other side of the fulcrum pin 2| in an outward direction. The extent of this outward movement is limited by engagement of stop shoulders 33, 33 on opposite sides of the cutter supporting members I9 with cooperable body stop shoulders 34, 34.

After the cutters 25 have been expanded outwardly by the expander springs 3| to their maximum extent, they can be locked in this position by alower tubular member 35 of the mandrel II, which is threaded into the kelly I4 and is provided with a lock ring 47 movable from an upper position in transverse alignment with inner supporting'member recesses 36, permitting retraction of the cutters, to a lower position opposite lugs 3'! formed on and projecting inwardly from the supporting member legs 23, preventing retraction of the cutters. The mandrel l I is normally held in its upper position with respect to the main body I 5 of the bitand the supporting members I9 by a helical retractor spring 38 en circling the tubular member 35, with its upper end engaging the mandrel shoulder 39 and its lower end engaging a spring seat 40 at the lower end of the hexagonal body socket I5a. This spring seat 4!] also serves as an upper bearing guide for the tubular mandrel member 35, whose lower end is slid-able within a lower bearing guide 4| below the lugs 37, which is integral with or secured to the depending body arms 20 of the main body of the bit. The two guides 40, 4| form a spaced two point support for the mandrel member 35 and assist it in resisting inward movement of the cutter legs 23 to retracted position during the reaming or cutting operation.

Circulating fluid can pass downwardly through the string of drill pipe B and through the tubular mandrel I for ejection from its lower discharge nozzle end onto the cutters 25, to cleanse them of cuttings and flush the latter from the drilling area to the top of the well bore. This circulating fluid is also availed of to unlatch the cutter supporting members I9 in the event it is desired to hold them positively in retracted position.

A positive lock may be provided by securing a hook 42 to the inner portion of each cutter supporting member below the lower mandrel guide 4|, and inserting the ends 43 of these hooks in holes 44 in a strip 45 extending across the outlet 35a of the mandrel. The cutting tool A, after being lowered in retracted position to a point at which the reaming operation is to begin, may be released for operation by starting the pumps at the surface of the well bore, which will force fluid down through the drill string B and mandrel II and impinge upon the latch strip 45, blowing or forcing it off the hook ends 43 and permitting the spring expanders 3| to shift the supporting arms 30 inwardly and the cutters 25 outwardly against the formation.

In the operation of the device, the tool A is mounted on the lower end of the drill string B with its parts held in retracted position by the latch strip 45, as shown in Figure 2. In this position of operation, the compressed retractor spring 38 holds the mandrel I I and its kelly I4 in an upward position with respect to the body I5, as determined by engagement of the kelly shoulder I6 with the body retainer ring I7. With the mandrel in this position, its lock ring 41 is elevated above the lugs 37 on the cutter supporting members I9, being received within the inner recesses 36 in the supporting members, which permits the latter to be held inwardly against the action of the expander springs 3|. The tool is lowered through the well casing, and upon reaching the position in the well bore below the casing shoe D at which the drilling operation is to begin, the pumps are started at the surface of the well bore and fluid impinged on the latch strip 45, to force it hydraulically ofi the ends 43 of the hooks 42 and release the cutter supporting members I9 for outward expansion under the influence of the springs 3|.

The drill string B is then rotated to rotate the main bit body I5 through the splined kelly and body connection I4a, I5a, the expander springs 3| forcing the arms 39 inwardly and the cutters 25 outwardly against the formation. Rotation is continued without moving the drill string longitudinally until the side cutters 25 enlarge the diameter of the hole to the maximum extent, as determined by eventual abutting of the supporting member stop shoulders 33 with the companion body stop shoulders 34. Thereafter, the drill string is lowered to cause the formation shoulder E produced in the well bore by the cutters 25 under the action .of the expander 3| to support the cutter members 25, I9 and body I5, and prevent their downward movement. Since the body I5 cannot move downwardly, drilling weight imposed on the drilling string B shifts its connected mandrel II downwardly within the body I5 againstthe action of the retractor spring 38 until the lower end 48 of the kelly I4 engages the upper spring seat and guide 4|]. When in this position, the mandrel lock ring 47 is disposed opposite and in alignment with the lugs 37 on the inner portions of the cutter supporting members I9, providing a positive lock by preventing inward movement of the cutters. So long as down weight is. imposed on the drill string B and the cutters 25 rest on the formation shoulder E, the iCutters are prevented from moving inwardly by engagement-of their lugs 31 with the mandrel look ring 41. It is also to be noted that further outward movement of the cutters beyond a predetermined maximum reaming diameter is prevented by contact between the supporting member shoulders 33 and the body shoulders 34, through which the drilling weight is transmitted to the roller cutters 25, thereby relieving the hinge pins 2I of this load.

Drilling is continued by rotating the drill bit and imposing the proper drilling weight on the cutters to cause their removal of the formation material and reaming of the hole in a downward direction for the desired extent or length. When it is desired to retract the drill bit and remove it to the top of the well bore, all that need be done is elevate the drill string B, which moves the side cutters 25 above the formation shoulder E and permits the retractor spring 38 to press downwardly on the body I5 and move it, together with the cutter supporting members I9, downwardly with respect to the mandrel II. This action repositions the mandrel lock ring 41 opposite the supporting member recesses 36 and above their lugs 31, permitting inward swinging of the cutters 25 and their supporting members I9 when the tool passes back into the casing upon elevation of the drill string. The cutters and their supporting members will ride the wall of the casing during elevation of the string until the too-1 is removed from the top of the well bore.

Pads in the form of longitudinal drag reaming blades 46 can be formed at the lower outer surface of the cutter supporting members I9, which will ride the inner wall of the casing and prevent the cutter teeth from hanging up in the casing coupling spaces while the tool is being lowered therein. These pads 46 can be provided in addition to the hooks 42 and latch strip 45, or in place of the latter. When the latching device is used, the tool can be lowered through open hole below the casing shoe D to as far a distance as desired before the reaming operation commences. If the latch is not provided, downward movement of the drill string B can be stopped when the bit passes out of the shoe D, and the drill pipe B and bit A rotated to allow the cutters 25 to produce the formation shoulder E under the influence of the compressed expander springs 3|. Drilling in a downward direction can then proceed as aforementioned, with the drill string B and mandrel II lowered against the action of the retractor spring 38 to position the lock ring 41 opposite the lugs 31 and prevent inward movement of the cutters 2-5 until the drilling weight is removed from the drilling tool.

It is, therefore, apparent that a drill bit of the expanding type has been provided, which can be used in substantially the same manner as an ordinary non-expanding drill bit. After the springs 3| have formed the shoulder in the formation, ordinary drilling procedure is followed simply by imposing the required downward weight on the drill bit and rotating it through the string of drill pipe to remove the formation material and enlarge the hole. When the bit is to be removed to the top of the well bore, it is only necessary to elevate the drill string, which will automatically elevate the mandrel I I with respect to the body I5 and remove its lock ring 4-! from locked position with respect to the lugs 31, permitting inward retraction of the supporting members I9 and their cutters 25 and withdrawal of the bit through the well casing.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A rotary well drilling bit, including a main body, cutter means mounted on said body, spring means engaging said cutter means for expanding said cutter means laterally outwardly, a mandrel adapted to be connected directly to a tubular drill string, said mandrel being slidably splined to said body and movable in one longitudinal direction within said body into engagement with said cutter means for preventing inward movement of said cutter means from its outwardly expanded position, and pring means engaging said mandrel and body for moving said mandrel in another longitudinal direction within said body to a position permitting such inward movement.

2. A notary well drilling bit, including a main body, cutter means mounted on said body, spring means engaging said cutter means for expanding said cutter means laterally outwardly, a mandrel adapted to be connected directly to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly within said body into engagement with said cutter means for preventing inward movement of said cutter means from its outwardly expanded position, and spring means engaging said mandrel and body for moving said mandrel in an upward direction within said body to a position permitting such inward movement.

3. A rotary well drilling bit, including a main body, cutter means pivotally mounted on said body and having an upwardly extending arm and a depending leg, spring means bearing against said body and arm for moving said arm inwardly and said leg outwardly, a mandrel adapted to be connected to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said leg for preventing inward movement of said leg from its outward position, and spring means engaging said mandrel and body for moving said mandrel in a relative upward direction within said body to a position permitting such inward movement of said leg,

4. A rotary well drilling bit, including a main body, cutter mean pivotally mounted on said body and having an upwardly extending arm and a depending leg, spring means bearing against said body and arm for moving said arm inwardly and said leg outwardly, a mandrel adapted to be connected to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said leg for preventing inward movement of said leg from its outward position, spring means engaging said mandrel and body for moving said mandrel in a relative upward direction in said body to a position permitting such inward movement of said leg, and stop means on said body and mandrel for limiting the extent of upward and downward movement therebetween.

5. A rotary well drilling bit, including a main body, cutter means pivotally mounted on said body and having an upwardly extending arm and a depending leg, spring means bearing against said body and arm for moving said arm inwardly and said leg outwardly, a mandrel extending downwardly within said body to a position adjacent said leg and adapted to be connected to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said leg for preventing inward movement of said leg from its outward position, a guide secured to said body and slidably receiving the lower end of said mandrel to support the latter, and spring means engaging said mandrel and bodyio'r mov ing said mandrel in a relative upward direction in said body to a position permitting'such inward movement of said leg.

6. A rotary well'drilling bit, including amain body, cutter means pivotally mountedon said body and having an upwardly extending arm and a depending leg, spring'means bearing against said body and arm for moving said arm inwardly and said leg outwardly, a mandrel extending downwardly within said body to a position adjacent said leg and adapted to be connected to a tubular drill string, said'mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said leg for preventing inward' movement of said leg from its outward position, a lower guide secured to said body and slidably receiving'the lower'end of said mandrel to support the latter, an upper guide in said' body slidably receiving said mandrel, and a spring engaging said upper guide and mandrel for moving said mandrel'in a. relative upward direction in said body to a position perinitting such inward movement of said leg.

7. A rotary well drilling bit, including a main body, opposed cutter means pivotally mounted on said body, each of said cutter means having an upwardly extending arm and a depending leg, a spring bearing against .each arm and said body for moving said arm inwardly and said leg outwardly, a mandrel extending downwardly within said body between said legs and adapted to be connected to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said leg for preventing inward movement of said legs'from their outward positions, and spring means engaging said mandrel and body for moving said mandrel in a relative upward direction in said'body to a'position permitting such inward movement of such legs.

8. 'A rotary well drilling bit, including a'main body, opposed supporting members pivotally mounted on said body, each of said supporting members having an upwardly extending arm and a depending leg, a cutter mounted on each of said legs, a spring bearing against each supporting member arm and said body for moving said supporting member arm inwardly and said leg' and its cutter outwardly, a mandrel extending downwardly within said body between said legs and adapted to be connected to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said legs for preventing inward movement of said cutters from their outward positions, and a spring within said body'engaging said mandrel for moving said mandrel in a relative upward direction in said body to a position permitting such inward movement of said cutters.

' 9. A rotary well drilling :bit, including a main body having a pair of opposed depending arms, opposed supporting members pivotally mounted on said body between said arms, each of said supporting members having an upwardly extending arm'and a depending leg, a roller cutter mounted on each of said legs, a spring bearing against each supporting member arm and said body for moving said supporting member arm inwardly and said leg and its cutter outwardly, a mandrel'extending cutter movement of said cutters from their outward positions, and spring means within said body engaging said mandrel for moving said mandrel in 'an upward direction relativeto said'body and legs to a position permitting such inward-movement of said cutters.

'10.. A-rotary'well drilling bit, including a main body having a pair of opposed depending arms, opposed supporting members pivotally mounted on said body between said arms, each of said supporting members having an upwardly extending arm and a depending leg, a roller cutter mounted on each'of said legs, a spring bearing against each supporting member arm and said body for moving said supporting member arm inwardly and said leg and its cutter outwardly, a mandrel extending downwardly between said body arms and adapted to be connected to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said legs for preventing inward movement of said cutters from their outward positions, a guide secured to said body arms and slidably receiving the lower end of said mandrel to support the latter, and spring means engaging said mandrel and body for moving said mandrel in an upward direction relative to said body and legs to a position permitting such inward movement of said cutters.

11. A rotary well drilling bit, including a main body having a central fluid passage, cutter means mounted on said body, spring means engaging said cutter means for expanding said cutter means laterally outwardly, latch means connected to said cutter means for holding said cutter means in an inward position against the action of said spring means, said latch means being disposed in the path of fluid flow through said central passage to be disconnected from said cutter means by fluid flowing through said passage.

12. A rotary well drilling bit, including a main body, opposed cutter means pivotally mounted on said body, each of said cutter means having an up :ardly extending arm and a depending leg, a

spring bearing against each arm and said body for moving said inwardly and said leg outwardly, a-tubular mandrel extending downwardly within said bod; between said legs and adapted to'be connected to a tubular drill string, said mandrel being slidably splined to said body and movable downwardly with respect thereto into engagement with said legs for preventing inward movement of said legs from their outward position, latch means connected to said legs for holdingihem inwardly against the action of said springs, said mandrel being adapted to direct iiuid onto said latch means to disconnect it from said legs to permit their outward movement.

13. A rotary well drilling bit, including a main body,'cutter means mounted onsaid body, means engaging-saidrcutter means for expanding said means laterally outward, a mandrel adapted to be connected directly to a drill string,

said mandrel being slidably splined to said body and movable in one longitudinal direction along said body into engagement with said cutter means for preventing inward movement of said cutter means from its outwardly expanded position, and

means engaging said mandrel and body for moving said mandrel in another longitudinal direction along said body to a position permitting such inward movement,

14. A rotary well drilling bit; including a main body; cutter means mounted on said body; a

mandrel slidably splined to said body and adapted for connection to a tubular drill string; means engaging said cutter means for expanding said cutter means laterally outward independently of movement of said mandrel along said body; and means on said mandrel movable with said mandrel in one longitudinal direction along said body, after expansion of said cutter means, into engagement with said cutter means for preventing inward movement of said cutter means. 15. A rotary well drilling bit; including a main body having a fluid passage therein; cutter means carried by said body; means engaging said cutter means for expanding said cutter means laterally outwardly; and movable obstructing latch means in the path of fluid flow through said passage for holding said cutter means in an inward position against the action of said expanding means.

ARCHER. W. KAMMERER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 465,103 Wegner Dec. 15, 1891 807,826 Irvine Dec. 19, 1905 1,043,723 Randolph Nov. 5, 1912 1,177,172 Craven Mar. 28, 1916 1,183,630 Bryson May 16, 1916 1,530,370 Jenkins et a1 Mar. 17; 1925 1,544,757 Hufford et al July 7, 1925 1,618,368 Dietle Feb. 22, 1927 2,187,483 Baker Jan. 16, 1940 

